Rose Valley is a small, historic borough in Delaware County, Pennsylvania, United States. Its area is 0.7 square miles (1.8 km²) and the population was 944 at the 2000 census. The area was settled by Quaker farmers in 1682, and later water mills along Ridley Creek drove manufacturing in the nineteenth century. In 1901 Rose Valley was founded as an Arts and Crafts community by architect Will Price, who bought 80 acres (320,000 m²) of land around the former Rose Valley textile mill, and Horace Traubel. Price and Traubel were both followers of the Henry George's economics (Georgism). Price also a co-founded Arden, Delaware, a utopian single tax community based on Henry George's economic model. Nevertheless the Georgist single-tax ideal was never implemented in Rose Valley. Crafts works soon foundered, leaving a legacy of impressive architecture, a preserved landscape, and a regional theatre, the Hedgerow Theatre (founded in 1923), as well as an artistic community that includes writers, painters, and architects.